1. Field of the Invention
The present invention relates generally to waist strengthening and rehabilitating apparatuses for strengthening and rehabilitating the waist including the lumbar vertebrae and the lumbar muscles, and more particularly to a waist strengthening and rehabilitating apparatus and load controller used in conjunction with the apparatus to produce desired load by controlling the flow direction and amount of working fluid.
2. Description of the Prior Art
Generally, around the waist region, the pelvis is connected to the vertebrae and two hip.joints are connected to the pelvis. Various lumbar muscles are connected to both pelvis and vertebrae, so that the pelvis can conduct movement relative to the vertebrae.
U.S. Pat. No. 5,928,112 discloses one of conventional waist strengthening and rehabilitating apparatuses that are used to strengthen or rehabilitate the waist.
However, the conventional waist strengthening and rehabilitating apparatus has a problem in a user's performing bending exercises in which the user sits up upright from a position where the waist is bent while the lower part of his body is firmly held by a thigh holding belt, as described below.
As shown in FIG. 1, the lower part of the body including the pelvis 1 is tightly held by the conventional apparatus in such a way that the knee 4 is raised up by a footrest 10 pushing the feet and the center portion of the thigh 3 is tied around al seat plate 12 by a belt 11 to bring the pelvis 1 into contact with the seat plate 12. However, in accordance with the conventional apparatus, only the femur 7 is tightly held by the belt 11, while the pelvis 1 is movable forward and rearward.
In more detail, in the conventional waist strengthening and rehabilitating apparatus, the knee 4 is raised up by elevating the footrest 10 from a position where the rear portion of the pelvis 1 is supported by a pelvis support 13, the feet 6 rest on the footrest 10 and a knee support 14 is situated at a proper height. As a result, the knee 4 is brought into contact with the knee support 14, but the lower portion of the thigh 3 becomes spaced apart from the seat plate 12. In this state, the center portion of the thigh 3 is tightly tied by the wide belt 11 to bring the pelvis 1 into contact with the seat plate 12.
When the center portion of the thigh is downwardly pushed by the belt 11, the waist seems to be tightly held by the conventional strengthening and rehabilitating apparatus, since the pelvis 1 is brought into contact with the seat plate 1 and the rear portion of the pelvis 1 is supported by the pelvis support 13. However, only the femur 7 is tightly held by the belt 11 and the pelvis 1 is movable forward and rearward, so that the pelvis 1 can be rotated around the hip joint 2, thus causing the lower part of the body to be somewhat freely movable.
Additionally, the rear portion of the pelvis 1 seems to be supported by the pelvis support 13, but shock absorbing space exists between the rear portion of the pelvis 1 and the pelvis support 13. Accordingly, this cannot be called a safe holding from the medical point of view.
When the center portion of the thigh 3 is tightly held by the belt 11 with the knee raised up by the footrest 10 pushing the feet 6, the pelvis 1 is brought into tight contact with the seat plate 12, but space is created between the thigh 3 and the seat plate 12. The space allows the thigh 3 to be moved, so that the thigh 3 is not tightly held by the apparatus.
In practice, when a user performs bending exercises in which he sits up straight from a position where the waist is bent, force resulting from the bending exercises is transmitted to feet through the pelvis 1, the femur 7 and the calf 5. The force exerted on the footrest 10 is increased in proportion to the force applied by a user. The sequential transmission of the reaction proceeding from the pelvis 1 to the feet 6 means that the bones and joints ranging from the pelvis 1 to the feet 6 are not properly held by the apparatus.
Though the waist seems to be tightly held by the conventional waist strengthening and rehabilitating apparatus because feet are laid on the footrest 10 and the buttocks is supported by the pelvis support 13, shock absorbing space exists between the pelvis 1 and the pelvis support 13. Consequently, the pelvis 1 should be moved rearward till the pelvis. 1 is brought into tight contact with the pelvis support 13, and the belt is tightened correspondingly.
The belt 11 is tightened to the center portion of the thigh 3. As a result, it is difficult for the pelvis 1 to be brought into contact with the seat plate 12 and a user may experience pain in his thigh caused by the tightening of the belt 11 so as to bring the pelvis 1 into the seat plate 12.
When a user performs bending exercises in which he sits up straight from a position where the waist is bent, force exerted on the footrest 10 and the tightness of the belt 11 are increased in proportion to force applied by the user. These prove that the waist is not held properly.
The holding of the lower part of the body should be performed so as to suppress the movement of the lower part, since force resulting from the bending exercises of the upper part of the body is exerted to the lower part, causing the lower part to move. However, the conventional waist strengthening and rehabilitating apparatus does not prevent the lower part from moving due to force resulting from the bending exercises of the upper part.
The lumbar vertebrae constituting the principal element of the waist consists of a plurality of vertebrae directly connected to one another without the aid of an additional support bone, and spinal nerves pass through the lumbar vertebrae, so that the lower part of the body including the pelvis should be tightly held during waist exercises. However, in the conventional waist strengthening and rehabilitating apparatus, the knees are held by a holding plate and the center portion of the thighs are tied to a seat by a belt, so that strengthening or rehabilitating effect is poor and accidents such as the fracture of a bone may occur in the case of the elderly and osteoporosis sufferers.
In addition, the conventional waist strengthening and rehabilitating apparatus has shortcomings in that it is difficult for a user to recognize the degree of tightness of the thigh holding belt and the thigh holding belt cannot be rapidly loosened in case of excessive tightening. When pain is excessive during strengthening or rehabilitation or preparation therefor, the thigh holding belt is not easily loosened, thereby causing a problem in safety.